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Marine Geotechnics
Heatflow and temperature gradients
Bremen Heat Probe
In situ sediment temperature and thermal conductivity measurements are carried out
using a 6 m-long heat flow probe (Lister-type violin bow design). The sensor strings contain 22 thermistors spaced at an interval of 26 cm and a heater wire along the entire length of the string. The electronics are integrated into the head of the probe. Four 8-channels 22-bit A/D converters are used to record temperature readings at a sampling interval of 1 s. The probe is operated in an autonomous or real time data mode.
Measurements are conducted in so called ‘pogo-style’, performing several
penetrations in a row at small distances. Each penetration consisted of raising the
probe some hundred meters above the sea floor from the previous penetration, slowly
moving the ship to the next penetration site and letting the wire angle become nearly
vertical before dropping the probe into the sediment for the next penetration.
In order to obtain thermal gradients that may be helpful in identifying sites of active fluid flow or mud volcanism, Miniaturised Temperature Data Loggers (MTL) are installed on outriggers attached to a 6 m gravity core barrel or mounted on a 4 m temperature lance (See pictures).
Diese Datenlogger sind eine gemeinsame Entwicklung der Universität Bremen und der Fima ANTARES. Sie sind autonom einsetzbar, robust, und auch für Langzeitmessungen geeignet. Mit einer einstellbaren Abtastrate von 1 s bis 10 Minuten ergeben sich Messzeiträume von 18 Stunden bis zu mehreren Jahren.
ROV high temperature lance
How hot are hot springs on the seabed? To investigate this question, a high-temperature lance was developed for ROV use. Direct data transmission allows the ROV pilot to make operational decisions. Temperature range 0 - 600°C, pressure range up to 600 bar.
